The brake discs of most wide-body commercial and military aircraft are made from carbon-carbon composites. Traditionally, C-C composites used as friction materials are produced by combining carbon fibers with a carbon matrix material that is deposited around the fibers using a Chemical Vapor Infiltration (CVI) process or a Chemical Vapor Deposition (CVD) process to provide the composites with the requisite density. Unfortunately, CVI/CVD processing is an expensive, capital intensive, and time-consuming process, frequently taking several months to complete. Therefore, there is a need for improvements to the densification procedure in the manufacture of C-C composite friction materials. Such desirable improvements would include reduction in capital investment, improvements to the mechanical and thermal properties of the composites, and improvement to the friction and wear performance of the friction material (e.g., aircraft brake discs) made from the composites.
US 200610279012 A1 (Simpson et al.) discloses a carbon fiber preform densification by pitch infiltration wherein the pitch infiltration step may be facilitated by the application of vacuum and/or pressure.
U.S. Pat. No. 4,318,955 (Kulakov et al.) discloses a method of making a carbon brake product wherein fibers are packed and then twice saturated with pyrocarbon, with a machining step therebetween, and heat treatment at 2000° C., to a final density of 1.75-1.8 g/cm.
U.S. Pat. No. 6,077,464 (Murdie et al.) discloses a method of making carbon-carbon composite materials which includes a variety of densification methods which may be used singularly or in various combinations. See e.g. column 4, lines 40-45.
U.S. Pat. No. 6,342,171 B1 (Murdie et al.) discloses a process of stabilizing a pitch-based carbon foam which includes densification of the foam with four cycles of combined VPI and PIC. See e.g. column 12, lines 8-40.
US 2004/0105969 A1 (Huang et al.) discloses manufacture of carbon composites which includes densification of the preform by resin or pitch via vacuum and pressure.